Protective helmet



FIG. 1 is a perspective view of a protective helmet showing our new design;

FIG. 2 is a rear view thereof;

FIG. 3 is a front view thereof;

FIG. 4 is a right side elevation view thereof;

FIG. 5 is a left side elevation view thereof;

FIG. 6 is a top plan view thereof; and,

FIG. 7 is a bottom plan view thereof. 

CLAIM We claim the ornamental design for a protective helmet, as shown and described. 